For many years pile products have been used, for example, in outer garments, shoes, carpets and wall coverings. In the carpet industry, conventional commercial processes for manufacturing such pile products call for tufting yarns through a suitable backing material such as woven polypropylene or jute yarns. One way to simplify the manufacture of pile products is to mold such products directly from thermoplastics. In such molding processes, a thermoplastic polymer is heated to its softening point and forced into a mold having cavities corresponding to the pile fibers. Examples of typical prior art molding processes are described in U.S. Pat. Nos. 3,027,595; 3,141,051; 3,317,644; 3,517,094; 3,632,842; 3,533,895; and 3,804,617.
In general, known molding processes required that the mold be cooled after the formation of the pile products so that the polymer solidifies sufficiently to permit the pile product to be removed from the mold. Such molding processes are acceptable provided the fibers have a configuration which lends itself to easy removal from the mold. Short, relatively thick fibers can be readily removed from the mold, but as the fiber length increases and the fiber diameter decreases, it becomes more difficult to remove such long thin fibers from the mold without severely damaging or deforming the fibers. Frequently, such long, thin fibers are pulled from the backing during removal from the mold to produce bare patches in the pile material, or they yield and stretch to produce areas where the pile fibers are severely elongated.